1. Field of the Invention
This invention relates generally to electronic gaming machines and more particularly to a method and apparatus for operating a gaming machine special feature that terminates on a positive result.
2. Description of the Prior Art
Casinos typically include electronic gaming machines (EGMs) such as slot machines and video poker machines. Slot machines, for example, usually include three reels that each have a plurality of symbols printed thereon. After the player applies a wager to the machine, he or she starts play by triggering a switch that starts the reels spinning. Each reel stops at a random position and thereby presents three symbol—one from each reel. Some combinations of symbols do not pay any jackpot. Others pay varying amounts according to predetermined combinations that appear in a pay table displayed on the machine and stored in the gaming machine's programmable read-on memory (PROM).
Competition for players among electronic gaming machines is tight and the industry is developing different methods for attracting and keeping players at their machines. One method for attracting players is to create linked progressive jackpot systems in which multiple gaming machines have been linked together into groups of machines that share the same bonus pool. A simple example of such a system is progressive video poker in which players play the primary poker game on one of a plurality of gaming machines grouped together on the casino floor. A coin-in counter, linked to all machines sharing the progressive pool, counts the total amount of money played in the group of machines and advances the progressive bonus pool accordingly. For instance, the casino can choose to set aside 5% of all money played on the group of video poker machines to the bonus pool. The amount of the pool is displayed on a large LED display and is incremented as money is played. This amount is awarded automatically as a bonus should a player on one of the video poker machines receive a designated winning hand such as a royal flush. After the bonus is awarded, the bonus pool is seeded with a nominal amount that is further incremented as described above.
The advantage of the progressive system is that the bonus pools from individual machines can be pooled to form larger awards that in turn attract more players. When taken to the extreme, progressive bonuses can be pooled together not only from machines in different areas of the casino, but also from different casinos in different states. More complex examples for bonusing are implemented using bonus servers over a network, such as disclosed in co-owned U.S. Pat. No. 6,319,125 (the '125 patent), which is incorporated herein by reference for all purposes. Also incorporated herein by reference for all purposes is U.S. Patent No. 5,655,961, assigned to the Assignee of the present application (the '961 patent), which also discloses bonuses that can be implemented by bonus servers over a network.
While these linked progressive systems have been effective at drawing additional players, there is a need for gaming machines that have additional attraction features and yet are not required to be linked to other machines. It is desired that the additional attraction feature include a positive ending result.